Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 211036
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
636 AM EDT TUE APR 21 2015

.SYNOPSIS...
A DEEP UPPER LEVEL TROUGH WILL PERSIST ACROSS THE GREAT LAKES AND
NORTHEAST FOR AT LEAST THE NEXT WEEK. UNDER THIS PATTERN...SOMEWHAT
UNSETTLED WEATHER CAN BE EXPECTED ACROSS THE REGION THROUGH FRIDAY
ALONG WITH TEMPERATURES FALLING TO BACK BELOW NORMAL...WITH THE
COLDER THAN NORMAL CONDITIONS THEN CONTINUING THROUGH THE WEEKEND
AND INTO EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1030Z...HAVE UPDATED THE FORECAST TO ACCOUNT FOR THE SMALL
AREA OF SHOWERS THAT BLOSSOMED OVER LAKE ERIE OVER THE PAST COUPLE
OF HOURS WITHIN A ZONE OF LOW LEVEL CONVERGENT FLOW...AND IS NOW
PUSHING INTO FAR WESTERN NEW YORK IN CONJUNCTION WITH A SMALL
SHORTWAVE. THESE SHOULD CONTINUE TO PUSH INLAND OVER THE NEXT 2-3
HOURS AND WEAKEN AS THEY MOVE AWAY FROM THE FAVORABLE AREA OF LOW
LEVEL CONVERGENCE OVER THE LAKE...BEFORE EVENTUALLY FALLING APART BY
MID TO LATE MORNING.

OTHERWISE...REGIONAL SURFACE ANALYSIS SHOWS A BAGGY COLD FRONT
DRAPED ACROSS EASTERN NEW YORK...WITH THIS BAGGINESS DUE TO A WEAK
WAVE OF LOW PRESSURE NOW SITUATED A LITTLE SOUTH OF THE CAPITAL
DISTRICT. BOTH OF THESE FEATURES WILL CONTINUE TO PUSH EASTWARD
THROUGH MID MORNING...AND AS A RESULT THEIR LINGERING ATTENDANT
SHOWER ACTIVITY ACROSS THE NORTH COUNTRY AND EASTERN FINGER LAKES
SHOULD CONTINUE TO TAPER OFF FROM WEST TO EAST THROUGH THAT TIME.

BEHIND THESE FEATURES...A DEEP UPPER LOW OVER THE UPPER GREAT LAKES
WILL SLOWLY MEANDER ITS WAY EASTWARD TO EASTERN ONTARIO PROVINCE
THROUGH THE COURSE OF TODAY AND TONIGHT...WITH ITS ATTENDANT COOL
POOL ALOFT CONTINUING TO SPREAD SOUTHEASTWARD ACROSS THE GREAT
LAKES. DIURNAL HEATING OF THIS COOLER AIRMASS ALOFT WILL RESULT IN
INCREASING DAYTIME INSTABILITY...AND THIS COUPLED WITH A SPOKE OF
SHORTWAVE ENERGY ROTATING THROUGH THE BASE OF THE UPPER LEVEL
CIRCULATION AND ACROSS OUR REGION WILL LEAD TO THE DEVELOPMENT OF
SOME DIURNALLY-DRIVEN SHOWERS...WITH THESE FOCUSING ON AREAS AWAY
FROM LAKE INFLUENCES LATER THIS MORNING AND THIS AFTERNOON. ACROSS
OUR AREA...THE GREATEST LIKELIHOOD OF THESE WILL BE FOUND FROM
INTERIOR PORTIONS OF THE SOUTHERN TIER NORTHEASTWARD ACROSS THE
FINGER LAKES AND INTERIOR PORTIONS OF THE NORTH COUNTRY...WHERE
INSTABILITY LEVELS MAY ALSO GET JUST HIGH ENOUGH TO SUPPORT A FEW
RUMBLES OF THUNDER DURING PEAK AFTERNOON HEATING. FURTHER TO THE
NORTH AND WEST...AREAS FROM BUFFALO NORTHEASTWARD TO ROCHESTER AND
WATERTOWN SHOULD REMAIN SHADOWED BY AN INCREASING SOUTHWESTERLY FLOW
OFF LAKES ERIE AND ONTARIO.

SPEAKING OF WHICH...BOTH THE 00Z NAM AND GFS HAVE CONTINUED TO TREND
NOTICEABLY STRONGER WITH THE LOW LEVEL JET THAT IS PROGGED TO
DEVELOP ACROSS LAKE ERIE/ONTARIO AND ADJOINING PORTIONS OF FAR
WESTERN NEW YORK DURING THE LATE MORNING AND EARLY AFTERNOON HOURS.
BOTH THE NAM AND GFS BUFKIT DATA NOW DEPICT 40-45 KNOT WINDS
EXTENDING AS LOW AS THE 1-2 KFT LAYER ACROSS THE NIAGARA FRONTIER
FOR A TIME THIS AFTERNOON...AND WITH A FAIR AMOUNT OF SUNSHINE/
RESULTANT DECENT MIXING EXPECTED TO DEVELOP IN THIS REGION...FEEL
THAT WE SHOULD BE ABLE TO PRETTY EASILY SOME OF THESE DOWN TO THE
SURFACE IN THE FORM OF SOME 40+ KNOT WIND GUSTS. WITH THIS IN
MIND...HAVE HOISTED A WIND ADVISORY FROM NIAGARA AND NORTHERN ERIE
COUNTIES OVER TO THE ROCHESTER AREA FROM 15Z-00Z TODAY...WITH THE
STRONGEST WINDS OF ALL LIKELY TO COME IN THE 18Z-21Z TIME FRAME...
BEFORE QUICKLY DIMINISHING LATE THIS AFTERNOON AND EARLY THIS
EVENING WITH DIMINISHING DIURNAL HEATING/MIXING.

LIKEWISE...ANY DIURNALLY-DRIVEN SHOWERS THAT DEVELOP ACROSS INTERIOR
SECTIONS TODAY SHOULD ALSO TEND TO DIMINISH WITH THE LOSS OF HEATING
THIS EVENING...BEFORE ADDITIONAL SHORTWAVE ENERGY ROTATING AROUND
THE CLOSED UPPER LOW BRINGS RENEWED CHANCES OF MORE GENERAL
SCATTERED SHOWERS DURING THE LATE EVENING AND OVERNIGHT HOURS...FOR
WHICH SOME CHANCE POPS WILL BE IN PLAY AREAWIDE. WHILE BOUNDARY
LAYER TEMPS SHOULD REMAIN WARM ENOUGH THROUGH THE NIGHT TO SUPPORT A
CONTINUATION OF MAINLY JUST PLAIN RAIN SHOWERS ACROSS THE LOWER
ELEVATIONS...SOME OF OUR HIGHER ELEVATIONS MAY SEE TEMPS COOL JUST
ENOUGH TO ALLOW FOR SOME WET SNOW SHOWERS TO MIX IN LATE TONIGHT...
ALBEIT WITH NO ACCUMULATION EXPECTED.

AS FOR TEMPS...850 MB READINGS WITHIN A COUPLE DEGREES EITHER SIDE
OF ZERO CELSIUS SHOULD BE SUPPORTIVE OF HIGHS MAINLY RANGING THROUGH
THE 50S TODAY...WITH THE COOLEST READINGS NORTHEAST OF THE LAKES AND
ACROSS THE HIGHER TERRAIN. FOLLOWING THIS...LOWS MOSTLY IN THE MID
TO UPPER 30S ARE EXPECTED FOR TONIGHT.

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
A WELL ADVERTISED HIGH LATITUDE BLOCKING PATTERN WILL BE IN PLACE
ACROSS NORTH AMERICA DURING THIS PERIOD...AND THIS WILL GUARANTEE
THAT WE WILL EXPERIENCE UNSETTLED AND INCREASINGLY CHILLY
CONDITIONS. THE UPPER LEVEL FLOW...WHILE FAMILIAR FROM RECENT
WINTERS FROM ITS PATTERN FORCING UPSTREAM RIDGE OVER THE CANADIAN
ROCKIES...IS UNIQUELY DIFFERENT. THIS BLOCKING PATTERN WILL BE
POLEWARD OF 40N LATITUDE...WHILE A SPLIT FLOW FEATURING A SEPARATE
CLOSED LOW WILL BE FOUND OVER THE SOUTHWEST PORTION OF THE COUNTRY.
IT WILL ULTIMATELY BE THIS SPLIT FLOW THAT WILL PREVENT US FROM
GETTING ANY PACIFIC MODIFICATION IN THE LONG TERM...AS THE GIST OF
ANY WARMING WILL STAY TO OUR SOUTH. MORE ON THIS IN THE LONG TERM
SECTION FOUND BELOW.

THIS PERIOD WILL OPEN UP ON WEDNESDAY WITH A PRONOUNCED RIDGE OVER
THE CANADIAN PRAIRIES...WHILE AN ANOMALOUSLY DEEP CLOSED LOW WILL BE
CENTERED JUST NORTH OF THE UPPER GREAT LAKES (IE. JUST NORTH OF THE
SOO). A 100KT H3 JETLET RACING ACROSS THE SOUTHERN PERIPHERY OF THE
CLOSED LOW WILL HELP TO SHOVE A COLD FRONT ACROSS THE LOWER GREAT
LAKES DURING THE MORNING...WITH A REINFORCING SHOT OF CHILLY AIR IN
ITS WAKE FURTHER DESTABILIZING THE LOWER BOUNDARY LAYER TO THE TUNE
OF 8 TO 9 DEG C/KM LAPSE RATES. THE FORCING FROM THE MORNING FROPA
AND SUBSEQUENT MIDDAY AND AFTERNOON INSTABILITY WITHIN A DEEP
CYCLONIC FLOW WILL SUPPORT AT LEAST SCATTERED RAIN SHOWERS...WITH
THE SOUTHERN TIER AND FINGER LAKES REGION MOST LIKELY TO PICK UP
MEASURABLE RAINFALL. IT WILL BE CHILLY AS WELL. H85 TEMPS AVERAGING
-4C WILL KEEP A LID ON OUR THERMOMETERS AS AFTERNOON HIGHS SHOULD
LARGELY BE IN THE 40S. FOR THE FAR WESTERN COUNTIES...A GUSTY
SOUTHWEST WIND OFF LK ERIE WILL EXACERBATE THE CHILL AND MAKE IT
FEEL ESPECIALLY RAW AS APPARENT TEMPS WILL BE IN THE 30S FOR THE
BULK OF THE DAY.

THE CIRCULAR UPPER LOW WILL BECOME MORE OBLONG AND STRETCH FROM
NORTHERN ONTARIO TO NEW ENGLAND DURING THE COURSE OF WEDNESDAY
NIGHT..AS A ROBUST SHORTWAVE ROUNDING ITS BASE WILL BEGIN THE
PROCESS OF FORMING A SECOND CLOSED LOW WITHIN THE BROADER MID LEVEL
CIRCULATION. THIS WHOLE PROCESS WILL KEEP A MOIST CYCLONIC FLOW IN
PLACE OVER OUR FORECAST AREA...WITH THE LIKELIHOOD OF AT LEAST ONE
MID LEVEL IMPULSE WITHIN THE LONGWAVE PATTERN. THERE IS NO WAY TO
TIME SUCH A PASSAGE AT THIS POINT...SO WILL MAINTAIN 40 POPS
REGIONWIDE. ANY SUBSEQUENT SHOWERS WILL THEN BE ACTED UPON BY THE
CONTINUING COLD ADVECTION...WHICH WILL SEND H85 TEMPS AS LOW AS -8C.
THESE LOWERING CLOUD BASE TEMPS WILL DEEPEN A BURGEONING DENDRITIC
GROWTH ZONE...AND WITH NEAR SFC TEMPS FORECAST TO DROP INTO THE LOW
TO MID 30S FOR MOST AREAS...THAT WILL TRANSLATE INTO SOME WET SNOW
SHOWERS.

ON THURSDAY...AN ELONGATED UPPER LOW FEATURING TWIN VORTICES WILL BE
CENTERED TO OUR NORTH WHILE A 990MB LOW WILL BE POSITIONED IN THE
VCNTY OF MAINE. THIS WILL MAINTAIN A MOIST CYCLONIC FLOW OVER OUR
FORECAST AREA WITH H85 TEMPS OF -8C STILL SUPPORTING AT LEAST AT
LEAST A MIX OF SNOW AND RAIN SHOWERS. FOR SOME AREAS LIKE THE
SOUTHERN TIER AND HIGHER TERRAIN OF THE FINGER LAKES...THE P TYPE
COULD SIMPLY BE JUST SNOW...ALTHOUGH QPF OF UNDER A TENTH OF AN INCH
SHOULD LIMIT ANY ACCUMS TO CARS AND ELEVATED SURFACES. TEMPS ON
THURS WILL BE EVEN LOWER THAN THE PREVIOUS RAW DAY...WITH MAX TEMPS
ONLY EXPECTED TO REACH INTO THE UPPER 30S (HIGHER TERRAIN) TO MID
40S. A FRESH WESTERLY WIND WILL PRODUCE APPARENT TEMPS IN THE 20S
ACROSS THE BULK OF THE SRN TIER...WHILE THE REMAINDER OF THE REGION
WILL EXPERIENCE WIND CHILLS IN THE 30S...THROUGHOUT THE WHILE DAY.
ISN`T LATE APRIL WEATHER FUN IN WESTERN/NORTH CENTRAL NEW YORK?

IT WILL BE DOWNRIGHT COLD ACROSS WESTERN AND NORTH CENTRAL NEW YORK
ON THURSDAY NIGHT...AS TEMPERATURES ARE FORECAST TO DROP INTO AT
LEAST THE LOWER 30S (UP 20S SRN TIER AND TUG HILL). THE GOOD NEWS IS
THAT GUIDANCE IS SUGGESTING A LULL IN THE PASSAGES OF MID LEVEL
IMPULSES...BUT THERE SHOULD STILL BE PLENTY OF CLOUD COVER OVER THE
REGION. THIS WILL ALL BE THE RESULT OF THE THE COMPLEX UPPER LOW TO
OUR NORTH...WHICH BY THE WAY IS FORECAST TO CONSOLIDATE INTO ONE
MAIN VORTICITY OVER THE LOWER ST LAWRENCE VALLEY. WHILE COLD WEATHER
OF THIS MAGNITUDE IS ALWAYS A CONCERN TO VEGETATION AT THIS TIME OF
YEAR...FRUIT AND FLOWERING TREES HAVE YET TO BLOSSOM...AND WITH AN
ABUNDANCE OF CLOUD COVER...THIS EVENT SHOULD PRODUCE ANY WIDESPREAD
IMPACTS.

ON FRIDAY...THE STACKED STORM SYSTEM WILL BE STATIONARY OVER THE
LOWER ST LAWRENCE VALLEY WHILE SOME RIDGING WILL MAKE AN ATTEMPT TO
PUSH ACROSS THE MISSISSIPPI VALLEY. THIS SCENARIO WILL ENCOURAGE
SOME DRY AIR TO WORK ACROSS THE UPPER GREAT LAKES...AND POSSIBLY AS
FAR EAST AS LAKE ERIE. MEANWHILE...THE POSITION OF THE UPPER LOW
WOULD PLACE OUR REGION IN A `FAVORABLE` AREA TO BE INFLUENCED BY ANY
SHORTWAVE PASSAGES. BOTH THE ECMWF AND GFS SUGGEST THE PRESENCE OF
CHANNELED VORTICITY OVER OUR REGION...SO GIVEN THE CONTINUED LOW
LEVEL INSTABILITY...WILL HAVE TO KEEP AT LEAST CHC POPS IN PLACE.
ONE CAN THUS INFER WITH A SOMEWHAT HIGH DEGREE OF CONFIDENCE THAT
THE VAST MAJORITY OF THE DAY WILL BE PCPN FREE. H85 TEMPS WILL
REMAIN AROUND -8C...SO MAX TEMPS ON FRIDAY SHOULD BE SIMILAR TO
THOSE FROM THE PREVIOUS DAY (UP 30S HIGHER TERRAIN TO MID 40S MOST
ELSEWHERE).

&&

.LONG TERM /SATURDAY THROUGH MONDAY/...
A WAVY SPLIT FLOW WILL BE FOUND OVER THE LOWER 48 DURING THIS
PERIOD...WHILE THE OLD CLOSED LOW RESPONSIBLE FOR THE CHILLY WEATHER
LEADING UP TO THIS PERIOD WILL ROTATE ACROSS THE CANADIAN MARITIMES.
THIS SCENARIO WILL ALLOW FOR A LITTLE PACIFIC MODIFICATION ACROSS
THE GREAT LAKES...BUT THE BULK OF ANY REAL WARMING WILL REMAIN TO
OUR SOUTH AND WEST. AS A RESULT...OUR TEMPERATURES WILL MODIFY TO
MORE TOLERABLE LEVELS WHILE STAYING BELOW NORMAL LATE APRIL VALUES.

IN TERMS OF PCPN...WHILE THERE WILL BE A MINIMAL CHANCE FOR A RAIN
OR SNOW SHOWERS SATURDAY AND SUNDAY...THE UPCOMING WEEKEND LOOKS TO
BE MUCH MORE SETTLED THAN THE PRECEDING DAYS. WILL LEAN MORE ON THE
ECMWF ENSEMBLES FOR MONDAY...WHICH SUGGESTS THE PASSAGE OF A
SHORTWAVE RIDGE WHICH WOULD SUPPORT FAIR DRY CONDITIONS.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
AS OF 1030Z...A SMALL AREA OF SHOWERS BLOSSOMED OVER LAKE ERIE OVER
THE PAST COUPLE OF HOURS WITHIN A ZONE OF LOW LEVEL CONVERGENT
FLOW...AND IS NOW PUSHING INTO FAR WESTERN NEW YORK IN CONJUNCTION
WITH A SMALL SHORTWAVE. THESE SHOULD CONTINUE TO PUSH INLAND OVER
THE NEXT 2-3 HOURS AND WEAKEN AS THEY MOVE AWAY FROM THE FAVORABLE
AREA OF LOW LEVEL CONVERGENCE OVER THE LAKE...BEFORE EVENTUALLY
FALLING APART BY MID TO LATE MORNING.

OTHERWISE...REGIONAL SURFACE ANALYSIS SHOWS A BAGGY COLD FRONT
DRAPED ACROSS EASTERN NEW YORK...WITH THIS BAGGINESS DUE TO A WEAK
WAVE OF LOW PRESSURE NOW SITUATED A LITTLE SOUTH OF THE CAPITAL
DISTRICT. BOTH OF THESE FEATURES WILL CONTINUE TO PUSH EASTWARD
THROUGH MID MORNING...AND AS A RESULT THEIR LINGERING ATTENDANT
SHOWER ACTIVITY ACROSS THE NORTH COUNTRY AND EASTERN FINGER LAKES
SHOULD CONTINUE TO TAPER OFF FROM WEST TO EAST THROUGH THAT TIME.

THROUGH THE MID MORNING HOURS...FLIGHT CONDITIONS SHOULD BE
LARGELY VFR... SAVE FOR SOME LOCALIZED MVFR CIGS ACROSS THE HIGHER
TERRAIN...AND WITHIN ANY LINGERING SHOWERS.

OTHERWISE FOR TODAY AND TONIGHT...A RATHER DEEP UPPER LEVEL LOW
WILL SLOWLY SHIFT FROM THE WESTERN GREAT LAKES TO CENTRAL ONTARIO
PROVINCE...WITH PROGRESSIVELY COOLER AIR FEEDING ACROSS OUR REGION
ALOFT. WITH INCREASING DIURNAL HEATING OF THIS COOL AIRMASS...EXPECT
SOME ADDITIONAL RAIN SHOWERS TO DEVELOP AWAY FROM THE STABILIZING
INFLUENCES OF THE LAKES TODAY...BEFORE GENERALLY DIMINISHING AGAIN
WITH THE LOSS OF HEATING THIS EVENING. LATER ON TONIGHT...MORE
GENERAL CHANCES FOR SCATTERED SHOWERS WILL RETURN AS ADDITIONAL
SHORTWAVE ENERGY ROTATES AROUND THE UPPER LOW...AND ACROSS OUR
REGION.

WHILE A FEW OF THE SHOWERS COULD PRODUCE BRIEF/LOCALIZED REDUCTIONS
TO MVFR VSBYS THIS AFTERNOON AND EVENING...IN GENERAL VFR CONDITIONS
ARE EXPECTED TO PREVAIL FROM LATE THIS MORNING THROUGH TONIGHT.

FINALLY...INCREASING DIURNAL HEATING/MIXING AND THE DEVELOPMENT OF A
40-45 LOW LEVEL JET WILL ALSO LEAD TO INCREASINGLY WINDY CONDITIONS
DURING THE LATE MORNING AND AFTERNOON HOURS NORTHEAST OF LAKE
ERIE...DURING WHICH TIME SOME SURFACE WIND GUSTS TO 40 KNOTS WILL BE
POSSIBLE FROM KBUF/KIAG OVER TO KROC. ANY SUCH WINDS THAT DO DEVELOP
SHOULD THEN RAPIDLY DIMINISH LATE THIS AFTERNOON AND EVENING WITH
THE LOSS OF HEATING.

OUTLOOK...
WEDNESDAY THROUGH SATURDAY...VFR/MVFR WITH SCATTERED TO OCCASIONALLY
MORE NUMEROUS RAIN SHOWERS...WHICH MAY BE MIX WITH AND/OR CHANGE TO
SNOW SHOWERS AT NIGHT.

&&

.MARINE...
A BRISK SOUTHWESTERLY FLOW IS EXPECTED ACROSS THE LOWER GREAT LAKES
TODAY...BEFORE DIMINISHING TONIGHT. AS OUTLINED BELOW...THIS HAS
NECESSITATED SMALL CRAFT ADVISORIES FOR MANY OF OUR NEARSHORE
ZONES...AS WELL AS THE SAINT LAWRENCE RIVER.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...WIND ADVISORY FROM 11 AM THIS MORNING TO 8 PM EDT THIS EVENING
     FOR NYZ001>003-010-011.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LEZ020-
         040-041.
         SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR
         LOZ042-043.
         SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR
         LOZ044-045.
         SMALL CRAFT ADVISORY FROM 11 AM THIS MORNING TO 8 PM
         EDT THIS EVENING FOR SLZ022-024.

&&

$$

SYNOPSIS...JJR
NEAR TERM...JJR
SHORT TERM...RSH
LONG TERM...RSH
AVIATION...JJR
MARINE...JJR






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